Psilocybin hallucinogen molecule. Computer model of a molecule of the hallucinogenic drug psilocybin. Atoms are represented as spheres and are colour-coded: carbon (light blue), hydrogen (white), oxygen (red), phosphorous (green) and nitrogen (dark blue). Psilocybin is a psychoactive alkaloid found in hundreds of species of mushrooms, known as magic mushrooms. When ingested it causes euphoria, hallucinations and an altered perception of time.